Pigmented paper and process of making same



Patented Nov. 19, 1940 UNITED STATES PATENT OFFICE PIGMENTED PAPER ANDPROCESS OF MAKING SAME Louis 0. Fleck, Appleton, Wia. aninior to PaperPatents Company, Neenah, Wis., a corporation 01 Wisconsin 12 Claims.

My invention relates to the manufacture of paper, and has to do moreparticularly with the incorporation with, or application to, papermaking materials or paper, of aluminum phosphate 6 pigments includingaluminum phosphate and aluminum phosphate complexes for improving thecolor and particularly the brightness or whiteness of finished paper.

' The present application is a continuation in V part of my co-pendingapplication, Serial No. 47,- 144, filed October 28, 1935, and is adivisional application of my co-p'ending application, Serial No.151,456, filed July 1, 1937. The present application is directed inparticular to the aluminum phosphate-calcium sulphite combinationpigments and complexes of the same.

Heretofore various inorganic materials have been used to fill paper andincrease its brightness or-light-refiecting index. The materials com- 20monly used are clay, talc, chalk, and the like. All clays, however, withwhich I am familiar have a much lower power of producing brightness inpaper than my materials. They are incorporated in paper primarily asfillers although they nec- 25 essarily have some pigmenting properties.My aluminum phosphate'compositions on the other hand are employed asfillers and coating compositions in place of other fillers and othercoating compositions primarily because of their unusual pigmentingproperties.

The principal object of my invention is to provide an improved paperpigment.

Another object of' my invention is to provide a paper pigment havinghigh brightness-imparting properties combined with low cost.

Another object of my invention is to provide a paper pigmentparticularly adapted for use'with paper materials containing substantialamounts of ground wood fibers.

A still further object of my invention is to provide a paper pigmenthaving a remarkable covering power.

Further objects will be apparent as the description hereinafterproceeds.

I have discovered that aluminum phosphate pigments and particularly thealuminum phosphate-calcium sulphite complexes to which the presentapplication isdirected, are of superior merit in the pigmenting of paperand have the added advantage of being less expensive than fillers andpigments of equivalent brightness such as titanium dioxide previouslyused. Although my invention is not to be limited by any theory ofoperation, the brightening power of my pigments appears to reside in theunusual covering power and ease with which, these compounds or complexesdistribute themselves on cellulosic fibers.

For a proper interpretation of the terms used in the specification andclaims, it is to be understood that the word pigment" refers to whitecompositions which are sufliciently insoluble under conditions of usemaking them suitable paper fillers and coating compositions, that theword filler includes material on the surface of the paper as well asthat which is incorporated in the sheet, that the words paper sheets"includes sheets of any thickness from thin tissue to thick board, andthat the words alkaline materials include alkali and alkaline earthmaterials and alkaline magnesium and zinc compounds.

The pigmenting compositions included in my invention comprise insolublealuminum phosphates and all insoluble white complexes containing thealuminum and the phosphate radicals. Alkali and alkaline earth-aluminumphosphate complexes which are insoluble under paper making conditionshave been found to be particularly good paper pigments.

In the preparation of my pigments which may be prepared in any suitablemanner such, for example, as by reacting compounds of aluminum withacids, oxides, or salts of phosphorus, by treatment of aluminum silicateclays or bauxite with phosphoric acid, or by treatment of other ores ornaturally occurring minerals of aluminum and phosphorus, it isespecially desirable that the conditions 01 reaction be so adjusted thatthe particle size of the precipitate be extremely small. This may beaccomplished by known technique as by adjusting concentration,temperature, order of addition of reagents, presence of protectivecolloids, etc. in accordance with known physical chemical principles.

It is also contemplated by my invention that 40 aluminum phosphatepigments may be precipitated in the presence of paper making fibers, inwhich case the pigment will be deposited directly onto the fibers, forexample, in the beater or.

chest or after the formation of the web; As an the phosphate radicalwhich are substantially insoluble under paper making. conditions andwhich might occur under varying conditions. Thus compounds coming withinmy invention may include acid or basic aluminum phosphates, doublephosphates as, for example, the double phosphate of aluminum andcalcium; and other modifications or compositions containing variousbasic or acid radicals which in view of the complex nature of themolecule are difiicult to anal'yze and assign a definite chemicalformula.

Aluminum phosphate complexes may also, within my invention, be used inadmixture with known or other suitable fillers or pigments applicable topaper manufacture, as, for example, clay, chalk, calcium sulphite,calcium phosphate, calcium sulphate, barium sulphate, etc. Such acombination may be a simple physical mixture although for some types ofpigments the use or precipitation .of my aluminum phosphate pig- I mentswith or on the other pigments has been foundto produce a combinationpigment having higher brightness-imparting characteristics in paper thaneither of the individual pigments when used alone and in likepercentages.

Of the combination pigments the calcium sulphite-aluminum phosphatecomposition or complex possesses unusual pigmenting properties. A

' paper containing a pigment, for example, consisting of about per centcalcium sulphite and 20 percent aluminum phosphate material has abrightness about equal to a paper containing an equal amount of apigment consisting of 100 percent aluminum phosphate material althoughthe brightness of a paper containing calcium sulphite is considerablylower than that of a paper containing an equal amount of my aluminumphosphate pigments. Another combination pigment consisting of 60 percentcalcium sulphite and 40 percent aluminum phosphate material produces abrightness greater than that of a pigment consisting of 100 percentaluminum phosphate pigmenting material. My investigations have led me tobelieve that in the above combinations a physical-chemical change occursresulting in a crystalline structure that is responsible for theimproved brightness-imparting properties in paper.

In general, when aluminum phosphate complexes are prepared for use inconnection with my invention, either in or out of the presence of papermaking fibers, such preparation may consist of the reaction, preferablyin water, of soluble salts containing aluminum, e. g. aluminum sulphate,aluminum nitrate, aluminum chloride, aluminum acetate, aluminum formate,sodium and potassium aluminates (alkali aluminates) etc., or an aqueousdispersion of aluminum hydroxides or aluminum sulphite etc. with solubleor insoluble compounds containing the phosphate radical, e. g. thephosphoric acids, the sodium phosphates, etc. The pH value of thereaction monium phosphates, magnesium phosphates, zinc phosphates, etc.The pH value of the reaction mixture may be adjusted to permit thedesired precipitation of the pigment. It the pH value is too low, thepigment may be modified by addition of an alkaline material such assodium hydroxide, calcium hydroxide, barium hydroxide, magnesium oxide,trisodium phosphate, sodium aluminate or sodium zincate, etc., or ifdesired, carbonates of the alkali and alkaline earth metals ormagnesium, etc. may be employed. I If the pH value is too high, it maybe lowered by the addition of acids such as phosphoric acid or acid.reactin salts such as aluminum sulphate, aluminum chloride, or aluminumsulphite, etc. In general, the pH range used is about 3.8 to 9, althougha range of 4.5 'to 5.5 is preferred. The precipitate should be white andsubstantially insoluble in pure water and, of course, be practicallyinsoluble under varying paper making conditions. When an alkalinematerial, such, for example, as calcium hydroxide is added as indicatedabove to raise the pH value, the resultant precipitate appears to be adouble salt of calcium and aluminum phosphate.

The brightness values in all cases mentioned through the specificationwere obtained employing the General Electric Reflectance meter using theNo. 1 or brightness filter. The General Electric Reflectance meter iswell known throughout the paper industry and is used almost exclusivelyfor making standard brightness comparative tests. The clay used in mycomparative tests is the ordinary Georgia Kaolin employed by the paperindustry.

The following examples will serve to illustrate my invention.

Example I About 600 pounds of sodium hydroxide and about 600 pounds ofaluminum hydrate are added to about 290 gallons of water and boiled forapproximately 20 to 30 minutes until the solution is clear. The solutionis diluted to about 720 gallons with water and then added slowly toabout 720 gallons of water to which separately but at the same timeabout 1640 pounds of 75 percent phosphoric acid diluted to 720 gallonswith water is being slowly added. To the above solution suflicient papermakers alum (aluminum sulphate) is added so that the final solution hasa pH value of approximately 5. The precipitate formed may be separatedby filtration in the usual manner.

In the above example the proportions on a dry basis are approximately 2parts alkali hydroxide, 2 parts aluminum hydrate, 4 parts phosphoricacid and 2 parts paper makers alum.

The pigment prepared by the method described above may be used invarying proportions with paper. A pigment may comprise for example, ashigh as about 30 percent by weight of the paper or as low as about 1percent by weight of the paper. A paper made up of 50 percent groundwood and 50 percent bleached sulphite fiber furnish and containing about2.5 percent of the pigment prepared by the method described in ExampleI, shows an improvement of approximately two points in brightness overpaper made with a similar fiber furnish without any filler andapproximately one point improvement in brightness over that obtainedfrom paper with the same fiber furnish containing 2.5 percent ordinaryclay filler. The improvement in brightness is plainly discernible to theeye, which is quite unusual.

The pigment prepared by the method described in Example I may also beemployed to advantage with other fillers. The'following examples willserve for purposes of illustration.

a. Paper made up of 50 percent ground wood and 50 percent bleachedsulphite fiber furnish and containing 20 percent by weight of inorganicfiller material consisting of percent ordinary clay and 5 percentaluminum phosphate pigment of Example I shows an improvement ofapproximately two points in brightness over paper made with a similarfurnish containing 20 percent all clay filler. Although the paper inthis example r 8,888,188 .-containlonly1percentbyweightoimyaluminumphosphate complex, the improvement in brightnemis of such magnitude asto be plainly discernible to the eye, and thus shows the remarkablepigmenting power oi m improved materials.

b. Paper made up oi 50 percent ground wood and 50 percent bleachedsulphite fiber furnish and containing. 20-percent inorganic fillermaterial consisting of 95 percent calcium sulphite and 5 percentaluminum phosphate li l ent of Example L'shows an improvement ofapproximately four points in brightness over paper made andapproximately one point improvement in brightness over'paper made with asimilar fiber and containing percent inorganic filler ma- 'terial,consisting of 85 percent clay and 15 percent of a mixture consisting of45 percent calcium sulphite and 55 percent aluminum phosphate pigment ofExample I, shows an improvement of approximately two points inbrightness over paper made with a similar fiber furnish containing 10percent of clay filler. This example in which my aluminum phosphatepigment represents only about 0.825 percent shows the remarkablepigmenting power of my Al PO4CaSO-a composition or complex when usedwith other fillers.

e. A paper made up of 50 percent ground wood and 50 percent bleachedsulphite fiber iurnish and containing percent inorganic filler materialconsisting of 60 percent clay and 40 percent of a mixture consisting 01'45 percent calcium sulphite and 55 percent aluminum phosphate pigment ofExample I, shows an improvement oi approximately 9.2 points inbrightness over paper made with the same fiber furnish without filler.This improvement is approximately 0.5 points lower than that obtainedfor paper made with a similar fiber furnish containing 20 percent 01'aluminum phosphate pigment oi Example I and is an improvement of about3.1 points in bri htness over a paper made from a similar fiber furnishcontaining 20 percent of clay filler. This example in which the fillercontains about 22 percent aluminum phosphate pigment or about 4.4percent based on the total weight of the paper, shows the effectivebrightening power of my aluminum phosphate complex-calcium sulphitepigment compositions.

j. A paper made of 50 percent ground wood and 50 percent bleachedsulphite fiber furnish and containing .20 percent inorganic fillermaterial consisting of 45 percent calcium sulphite and 55 percentaluminum phosphate pigment oi Example I. shows an improvement 0!approximately 10.7 points in brightness over paper made from a similarfiber furnish containing no added filler. This improvement is greater byapproximately one point than that obtained for paper made with a similarfiber furnish containing 20 percent of aluminum phosphate pigment ofExample I and is an improvement of about 4.4 points in brightness overpaper made from a similar fiber furnish containing 20 percent all clayfiller. This example in which the aluminum phosphate pigment represents11 percent of the weight of the paper and the calcium sulphiterepresents 9 percent of the weight of the paper, illustrates theremarkable pigmenting power of my pigment when used with calciumsulphite.

g. A paper made of 50 percent ground wood and 50 percent bleachedsulphite fiber furnish and containing 20 percent inorganic fillermaterial consisting of 95 percent calcium phosphate and 5 percentaluminum phosphate pigment of Example I, shows an improvement ofapproximately' 1.1 points in brightness over paper made from a similarfiber furnish filled with 20 percent all calcium phosphate filler and isan improvement of approximately 2.2 points in brightness over paper madefrom a similar fiber furnish and filled with an all clay filler of thesame pigment content.

Example II About 558 pounds of '75 percent pho phoric acid diluted with558 pounds of water are mixed with about 720 pounds of iron-free papermakers alum dissolved in about '720 pounds of water. To this mixture isadded an aqueous calcium hydroxide suspension containing approximately100 grams of Ca(OH) 2 per liter of water until the pH value has beenraised to about 5.0 to 5.2. The calcium aluminum phosphate complexprecipitate obtained is an extremely good paper pigment. The followingexamples will serve for purposes of illustration.

h. A paper made of 50 percent ground Wood and 50 percent'bleachedsulphite fiber furnish and containing 20 percent inorganic fillermaterial consisting of the aluminum phosphate pigment of Example IIshows an improvement, of approximately 10 points in brightness overpaper made with a similar fiber furnish containing no added filler andan improvement of 5.5 points in brightness over paper made with asimilar fiber furnish filled with 100 percent clay to the same pigmentcontent. This improvement is of the same magnitude as that obtained withaluminum phosphate pigment of Example I.

i. A paper made of 50 percent ground Wood and 50 percent bleachedsulphite fiber furnish and containing 2.5 percent inorganic fillermaterial consisting of the aluminum phosphate pigment of Example II,shows an improvement of approximately 2 points in brightness over papermade with a similar fiber furnish containing no added filler and animprovement of more than one point in brightness over paper made with asimilar fiber furnish filled with 100 percent clay filler to a pigmentcontent of 2.5 percent.

Example III About 975 pounds of 75 percent phosphoric acid and about 780pounds of 95 percent sulphuric acid are mixed with 5800 pounds of water.About 585 pounds of aluminum hydrate are added to the above acid mixturewhich is then heated to a boil for approximately 20 to minutes untilSimilarly, an aluminum phosphate complex may be prepared by mixing anaqueous solution of acid calcium phosphate (obtained for example byextraction from triple super phosphate fertilizer) with alum (aluminumsulphate) and calcium hydroxide. This pigment may be used to advantagewith calcium sulphate, the pigment or filler mixture showing a decidedimprovement in brightness over a filler of 100 percent calcium sulphiteused in like percentages.

Example V Similarly, an aluminum phosphate complex may be prepared bymixing in water aluminum sulphite and phosphoric acid and suilicientalkaline material, such as sodium aluminate, calcium hydroxide, bariumhydroxide, barium carbonate or magnesium carbonate, etc. to raise the pHvalue to about 3.8 to 5.5. If the pH value goesover to the alkalineside, i, e. pH 7 or 8, it may be lowered to the preferred value byadding alum or additional aluminum sulphite.

Example VI The phosphoric acid used in the preceding Examples, I, II andIII or the calcium phosphate used in Example IV may be replacedpartially or in whole by alkali phosphates such as sodium phosphate,particularly the disodium phosphate. Thus, for example, by mixing 50.9pounds of disodium phosphate in 191 pounds of water, with 59 pounds ofalum in 87 pounds of water, and adjusting the pH value to 3.8 to 9 withalkali or alkaline oxides, hydroxides or carbonates, an aluminumphosphate complex precipitate is obtained having good pigmentingproperties.

When using my aluminumphosphate pigments with calcium sulphite and clay,for instances, Georgia kaolin, it has been found desirable to usebetween 10 and 30 percent aluminum phosphate pigment, 15 and 45 percentcalcium sulphite and and 75 percent clay, the preferred ratio ofaluminum phosphate pigment to calcium sulphite being approximately 40 to60 percent. Paper, for example, containing about 10 percent of'more ofinorganic filler material comprising 24 percent'aluminum phosphatepigment (e. g. Example I), 36 percent calcium sulphite and 40 percentclay has been found to possess an extremely high brightness. Anotherfiller mixture coming within the preferred range consists of 18 percentaluminum phosphate pigment (e. g. Example II or III), 27 percent calciumsulphite and 55 percent clay. The ,paper made using the above inorganiccompositions contains ordinarily at least 10 percent filler material atleast 1 percent of which is aluminum phosphate pigment.

Coating pigments Where the aluminum phosphate complexes are to be usedas a coating pigment, they may replace all or part of the pigments suchas clay, etc., generally used for coating paper. For this purpose it iscustomary to have the pigment so treated that it is at a pH value ofapproximately 5.0 to 8.5 and preferably 6.5 to'7.0 before addingadhesive material, such as casein, starch, soya bean protein, etc. v

I have found that paper sheets coated with a clay coating compositioncontaining about 1 percent aluminum phosphate pigment based on themineral ingredients employed and made for example as described inExample I show an increase in brightness of abOut Qne point over sheetssimilarly' coated merely -with the clay coating composition. I 'havealso found thatpaper sheets coated with a calcium sulphite coatingcompositioncoritaining-"about 7.5 percent of aluminum phosphate pigmentbased upon mineral ingredients employed show an increase in brightnessof about one point over sheets similarly coated merely with the calciumsulphite coating composition. While the above coating compositionscontain a relatively small percentage of my aluminum phosphate pigments,and show an increase in brightness of only one point over the othercoating compositions, the increase is perceptible to the eye and is ofgreat commercial importance in the paper industry. When an extremelyhigh brightness is desired, I have discovered that paper sheets coatedwith a coating composition in which the only mineral ingredient employedis my aluminum phosphate pigment will have a brightness of approximatelyfourteen points higher than sheets coated with a clay coatingcomposition and approximately 10.5 points higher than sheets coated witha. calcium sulphite coating composition, all coating compositionsemploying the same proportion of mineral ingredients. Ordinarily themineral ingredients of my coating compositions will contain at least 5percent of my aluminum phosphate pigments although when theGermanson-Kranhold process described in U. S. Patent No. 1,918,095,dated July ll, 1933, is being used, I prefer to use a coatingcomposition containing at least about 10 percent of my aluminumphosphate pigment. The references above to increased brightness refer topapers containing at least ten pounds of coat per ream. In case lightercoatings are employed the improved brightness corresponds to the amountof coating.

The following examples will serve to illlustrate the preparation ofpigments particularly adapted for coating purposes.

Example VII About 600 pounds of sodium hydroxide and about 600 pounds ofaluminum hydrate are added to about 290 gallons of water and boiled forapproximately 20 to minutes until the solution is clear. The solution isdiluted to about 720 gallons with water and then added slowly to about720 gallons of water to which separately but at the same time about 1640pounds of '75 percent phosphoric acid diluted to 720 gallons with wateris being slowly added with vigorous agitation. The pH value of the finalmixture is Example VIII About 107 pounds of 75 percent phosphoric acidand about 134 pounds of paper makers alum are dissolved in approximately900 pounds of water and stirred until a clear solution is obtained.About 385 pounds of barium hydroxide (hydrated) is dissolved in about2100 pounds of water at approximately 45% C. The acid-alum solution andthe barium hydroxide solution are then added separately but at the sametime to about 800 pounds of water. The pH value of the final mixture isapproximately 6.5. The precipitate formed may be recovered by filtrationin the usual manner. This pigment may also be sized with casein, starch,etc., by recognized methods to give coating solutions having a pH valueof 6 to 8.5. This pigment may be mixed with other paper pigments orpreferably com-- bined with other pigments in a manner similar to thatof coating pigment, Example VII.

Example IX A 25 percent aqueous solution of about 23 pounds of disodiumphosphate is vigorously mixed with a 25 percent aqueous solution ofabout 27 pounds oi paper makers alum. The precipitate formed may befiltered and washed-and made up to a slip of suitable consistency andtreated with alkaline material such as trisodium phosphate, calciumhydroxide, sodium bicarbonate, etc. to bring the pH value up toapproximately 5.0 to. 7.0. This pigment slip may also be sized withcasein, starch, soya bean protein, glue or other adhesives according tothe well known practices of the art. The coating mixtures may be treatedif desired in a ball mill or colloidal mill to insure good dispersion.

In the above filler and coating examples it will be understood that mypigments may be used under varying conditions according to well knownpractices in the art. For example, it will be understood that myinvention is not limited by the preferred order of addition of thevarious materials, equally good results being obtained when the alkalinematerials are added to the acid materials or vice versa. It will also beunderstood by those skilled in paper manufacture that the common sizingcompositions including alum, rosin, starch and the like may be used inconjunction with my novel pigmenting compositions.

It will also be understood by those skilled in the art that the oxidesor carbonates of alkaline materials, including the alkali and alkalineearth metals, are considered to be equivalents of the hydroxides and maybe used in place of the hydroxides by properly adjusting theproportions, etc.

While my invention is not limited to any particular theory, myinvestigations lead me to believe that my improved pigmentingcompositions possess a remarkable covering power as shown by the easewith which they plate" or distribute themselves on the cellulosicfibers. When my aluminum phosphate complexes are used in conjunctionwith other fillers they not only improve the brightness of the mixtureor combination pig ment, but in addition appear to impart to thecomposition or mixture the remarkable covering power. The molecularstructure of my pigments along with their absorptive power are believedimportant factors in my improved compositions or complexes.

My pigments may be used in any furnish but have been found of particularvalue for use in a furnish containing ground wood fibers, where it hasbeen known for some time that ordinary alkaline fillers such as calciumcarbonate should not generally be used when a white sheet is desired.The ground wood containing all of the 5 organic and inorganic materialsof natural wood such as lignin, tannins, etc. darkens in color in analkaline medium. Extensive investigation, however, employing my aluminumphosphate piginents with paper sheets containing 0, 10, 50 or even 95percent ground wood have given excellent results, the paper retainingits high brightness or whiteness under varying conditions.

Numerous other applications of my invention will doubtless suggestthemselves to those skilled in the art without departing from the spiritof my invention. Hence, I do not wish to be limited to the specificdetails or embodiments disclosed herein,- but intend that the scope ofmy invention shall be determined from the appended claims, which shouldbe interpreted asbroadly as the state of the art will permit.

I claim:

1. Paper containing mineral pigmenting material having as essentialelements an aluminum phosphate pigment and calcium sulphite, thepigmenting material of said paper being madeup of at least five per centof said aluminum phosphate pigment.

2. As an article of manufacture, a paper sheet 80 containing a fillermaterial comprising aluminum phosphate pigment and calcium sulphite,said filler consisting of at least five percent aluminum phosphatepigment and said sheet containing at least one percent of said aluminumphosphate pigment.

3. As an article 0. manufacture, a paper sheet containing about twentypercent filler material comprising calcium sulphite and at least five.percent aluminum phosphate pigment.

4. As an article of manufacture, a paper sheet containing at least tenpercent of a filler material comprising pre-formed aluminum phos- Iphate pigment, calcium sulphite and clay, said filler material beingmade up of at least five per cent ofsaid aluminum phosphate pigment.

5. As an article of manufacture, a paper sheet containing a fillermaterial comprising about ten to thirty percent aluminum phosphatepigment, about fifteen to forty-five percent calcium sulphite and abouttwenty-five to seventy-five percent clay.

6. As an article of manufacture, a paper sheet containing a fillermaterial consisting of at least forty percent clay and the remaindercomprising aluminum phosphate pigment and calcium sulphite, said fillermaterial containing at least five per cent of said aluminum phosphatepigment.

7. As an article of manufacture, a paper sheet containing a fillermaterial consisting of about forty percent clay, about twenty-fourpercent aluminum phosphate pigment and about thirtysix percent calciumsulphite.

8. As an article of manufacture, a paper sheet containing a fillermaterial consisting of about fifty-five percent clay, eighteen percentaluminum phosphate pigment and about twenty-seven percent calciumsulphite.

9. As an article of manufacture, a paper sheet 7 containing at leastabout ten percent of a filler material comprising an aluminum phosphatepigment and calcium sulphite, said sheet being made up of at least onepercent of said aluminum phosphate pigment and containing less than tenper- 75 cent calcium sulphite and said filler material being made up orat least five percent of said aluminum phosphate pigment and containingless than fifty percent calcium sulphite.

10. As an article of manufacture. a paper sheet containing a fillermaterial comprising a substantial proportion 01' an aluminum phosphatepigment and a minor proportion or calcium sulphite, said filler materialcontaining at least ten percent of said aluminum phosphate pigment.

11. The improvement in the art oi manufacturing a filled papercontaining as essential ingredients wood fibers and filler materialwhich comprises forming said filled paper-by applying to said fibers analuminum phosphate pigment and calcium sulphite, the filler material ofsaid paper being made up 0! at least five percent of said aluminumphosphate pigment.

12. The improvement in the art of manufacturing a pigmented papercontaining as essential ingredients wood fibers and mineral pigmentingmaterial which comprises forming said pigmented paper by forming a paperweb and applying to said web a pigmenting material containing analuminum phosphate pigment and calcium sulphite, said pigmentingmaterial containing at least five percent of said aluminum phosphatepigment.

CERTIFICATE or CORRECTION. Patent No. 2,222,199. November 19, 19b0,

LOUIS c FLECK.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: P3362,first column, lines 62 and 65, for the words "phosphates, etc. ThepHvalue' of the reaction mcnium phosphates" read -phosphatea,. thevarious calcium phosphates, ammonium phosphates'--; page 14., secondcolumn, line 58, for "5 percent" read --about 5 percent--; page 5, firstcolumn, line 8, for "14.5% C." read "145 C.--} and that the said LettersPatent shouldbe read with this correction therein that the same mayconform to the record of the case in the Patent Office. I I

Signed and sealed this 21st day of January, A. D. 191 1.

Henry Van Arsd ale, (Seal) Acting Commissioner of Patents.

